--- a/roundup/cgi/templating.py	Wed Jul 25 11:42:02 2018 +0000
+++ b/roundup/cgi/templating.py	Wed Jul 25 11:42:51 2018 +0000
@@ -1859,7 +1859,7 @@
 
         ret = date.Date('.', translator=self._client)
 
-        if isinstance(str_interval, basestring):
+        if is_us(str_interval):
             sign = 1
             if str_interval[0] == '-':
                 sign = -1
@@ -1896,7 +1896,7 @@
             if default is None:
                 raw_value = None
             else:
-                if isinstance(default, basestring):
+                if is_us(default):
                     raw_value = date.Date(default, translator=self._client)
                 elif isinstance(default, date.Date):
                     raw_value = default
@@ -2874,7 +2874,7 @@
         """
         q = urllib_.quote
         sc = self.special_char
-        l = ['%s=%s'%(k,isinstance(v, basestring) and q(v) or v)
+        l = ['%s=%s'%(k,is_us(v) and q(v) or v)
              for k,v in args.items() if v != None ]
         # pull out the special values (prefixed by @ or :)
         specials = {}

--- a/roundup/date.py	Wed Jul 25 11:42:02 2018 +0000
+++ b/roundup/date.py	Wed Jul 25 11:42:51 2018 +0000
@@ -38,6 +38,7 @@
         return (a > b) - (a < b)
 
 from roundup import i18n
+from roundup.anypy.strings import is_us
 
 # no, I don't know why we must anchor the date RE when we only ever use it
 # in a match()
@@ -765,7 +766,7 @@
             arith_types = (int, float)
         if isinstance(spec, arith_types):
             self.from_seconds(spec)
-        elif isinstance(spec, basestring):
+        elif is_us(spec):
             self.set(spec, allowdate=allowdate, add_granularity=add_granularity)
         elif isinstance(spec, Interval):
             (self.sign, self.year, self.month, self.day, self.hour,